Blades with functional balance asymmetries for use with ultrasonic surgical instruments

ABSTRACT

Disclosed is an ultrasonic surgical instrument that combines end-effector geometry to best affect the multiple functions of a shears-type configuration. The shape of the blade is characterized by a radiused cut offset by some distance to form a curved geometry. The cut creates a curved surface with multiple asymmetries causing multiple imbalances within the blade. Imbalance due to the curve of the instrument is corrected by a non-functional asymmetry proximal to the functional asymmetry. Imbalance due to the asymmetric cross-section of the blade is corrected by the appropriate selection of the volume and location of material removed from a functional asymmetry. The shape of the blade in one embodiment of the present invention is characterized by two radiused cuts offset by some distance to form a curved and potentially tapered geometry. These two cuts create curved surfaces including a concave surface and a convex surface. The length of the radiused cuts affects, in part, the acoustic balancing of the transverse motion induced by the curved shape.

This application is related to the following copending patentapplications: application Ser. No. 08/948,625 filed Oct. 10, 1997;application Ser. No. 08/949,133 filed Oct. 10, 1997; application Ser.No. 09/106,686 filed Jun. 29, 1998; application Ser. No. 09/337,077filed Jun. 21, 1999; application Ser. Nos. 09/412,557; 09/412,996; and09/413,225 which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates, in general, to ultrasonic surgicalinstruments and, more particularly, to multifunctional curved bladeswith functional asymmetries for use with ultrasonic surgical instrumentsto minimize undesirable motion.

BACKGROUND OF THE INVENTION

Ultrasonic instruments, including both hollow core and solid coreinstruments, are used for the safe and effective treatment of manymedical conditions. Ultrasonic instruments, and particularly solid coreultrasonic instruments, are advantageous because they may be used to cutand/or coagulate organic tissue using energy in the form of mechanicalvibrations transmitted to a surgical end-effector at ultrasonicfrequencies. Ultrasonic vibrations, when transmitted to organic tissueat suitable energy levels and using a suitable end-effector, may be usedto cut, dissect, or cauterize tissue. Ultrasonic instruments utilizingsolid core technology are particularly advantageous because of theamount of ultrasonic energy that may be transmitted from the ultrasonictransducer through the waveguide to the surgical end-effector. Suchinstruments are particularly suited for use in minimally invasiveprocedures, such as endoscopic or laparoscopic procedures, wherein theend-effector is passed through a trocar to reach the surgical site.

Ultrasonic vibration is induced in the surgical end effector by, forexample, electrically exciting a transducer which may be constructed ofone or more piezoelectric or magnetostrictive elements in the instrumenthand piece. Vibrations generated by the transducer section aretransmitted to the surgical end-effector via an ultrasonic waveguideextending from the transducer section to the surgical end-effector. Thewaveguides and end-effectors are designed to resonate at the samefrequency as the transducer. Therefore, when an end-effector is attachedto a transducer the overall system frequency is still the same frequencyas the transducer itself.

The amplitude of the longitudinal ultrasonic vibration at the tip, d,behaves as a simple sinusoid at the resonant frequency as given by:

d=A sin (ωt)  (equation 1)

where:

ω=the radian frequency which equals 2π times the cyclic frequency, f;and

A=the zero-to-peak amplitude.

The longitudinal excursion is defined as the peak-to-peak (p-t-p)amplitude, which is just twice the amplitude of the sine wave or 2A.

Solid core ultrasonic surgical instruments may be divided into twotypes, single element end-effector devices and multiple-elementend-effector. Single element end-effector devices include instrumentssuch as scalpels, and ball coagulators, see, for example, U.S. Pat. No.5,263,957. While such instruments as disclosed in U.S. Pat. No.5,263,957 have been found eminently satisfactory, there are limitationswith respect to their use, as well as the use of other ultrasonicsurgical instruments. For example, single-element end-effectorinstruments have limited ability to apply blade-to-tissue pressure whenthe tissue is soft and loosely supported. Substantial pressure isnecessary to effectively couple ultrasonic energy to the tissue. Thisinability to grasp the tissue results in a further inability to fullycoapt tissue surfaces while applying ultrasonic energy, leading toless-than-desired hemostasis and tissue joining.

The use of multiple-element end-effectors such as clamping coagulatorsinclude a mechanism to press tissue against an ultrasonic blade, thatcan overcome these deficiencies. A clamp mechanism disclosed as usefulin an ultrasonic surgical device has been described in U.S. Pat. Nos.3,636,943 and 3,862,630 to Balamuth. Generally, however, the Balamuthdevice, as disclosed in those patents, does not coagulate and cutsufficiently fast, and lacks versatility in that it cannot be used tocut/coagulate without the clamp because access to the blade is blockedby the clamp.

Ultrasonic clamp coagulators such as, for example, those disclosed inU.S. Pat. Nos. 5,322,055 and 5,893,835 provide an improved ultrasonicsurgical instrument for cutting/coagulating tissue, particularly looseand unsupported tissue, wherein the ultrasonic blade is employed inconjunction with a clamp for applying a compressive or biasing force tothe tissue, whereby faster coagulation and cutting of the tissue, withless attenuation of blade motion, are achieved.

Improvements in technology of curved ultrasonic instruments such asdescribed in U.S. patent application Ser. No. 09/106,686 previouslyincorporated herein by reference, have created needs for improvements inother aspects of curved clamp coagulators. For example, U.S. Pat. No.5,873,873 describes an ultrasonic clamp coagulating instrument having anend effector including a clamp arm comprising a tissue pad. In theconfiguration shown in U.S. Pat. No. 5,873,873 the clamp arm and tissuepad are straight.

The shape of an ultrasonic surgical blade or end-effector used in aclamp coagulator device defines at least four important aspects of theinstrument. These are: (1) the visibility of the end-effector and itsrelative position in the surgical field, (2) the ability of theend-effector to access or approach targeted tissue, (3) the manner inwhich ultrasonic energy is coupled to tissue for cutting andcoagulation, and (4) the manner in which tissue can be manipulated withthe ultrasonically inactive end-effector. It would be advantageous toprovide an improved ultrasonic clamp coagulator optimizing these fouraspects of the instrument.

However, as features are added to ultrasonic surgical instrument blades,the altered shape and asymmetries cause the blade to become unbalanced,meaning that the blade has the tendency to vibrate in directions otherthan the longitudinal direction along the length of the instrument. U.S.patent application Ser. No. 09/106,686 previously incorporated herein byreference, addressed balancing blades proximal to functional asymmetriesusing balance asymmetries. While U.S. patent application Ser. No.09/106,686 has proven eminently successful at balancing blades andwaveguides proximal to the balance asymmetry, there are someapplications where some balancing may be desirable within the functionalportion of an asymmetric blade.

It would be desirable to provide a balanced ultrasonic surgicalinstrument blade within the functional area of the blade to optimizeinstrument performance. The blade described herein has been developed toaddress this desire.

SUMMARY OF THE INVENTION

Disclosed is an ultrasonic surgical instrument that combinesend-effector geometry to best affect the multiple functions of ashears-type configuration. The shape of the blade is characterized by aradiused cut offset by some distance to form a curved geometry. The cutcreates a curved surface with multiple asymmetries causing multipleimbalances within the blade. Imbalance due to the curve of theinstrument is corrected by a non-functional asymmetry proximal to thefunctional asymmetry. Imbalance due to the asymmetric cross-section ofthe blade is corrected by the appropriate selection of the volume andlocation of material removed from a functional asymmetry. The shape ofthe blade in one embodiment of the present invention is characterized bytwo radiused cuts offset by some distance to form a curved andpotentially tapered geometry. These two cuts create curved surfacesincluding a concave surface and a convex surface. The length of theradiused cuts affects, in part, the acoustic balancing of the transversemotion induced by the curved shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. The invention itself, however, both as toorganization and methods of operation, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription, taken in conjunction with the accompanying drawings inwhich:

FIG. 1 illustrates an ultrasonic surgical system including anelevational view of an ultrasonic generator, a sectioned plan view of anultrasonic transducer, and a partially sectioned plan view of a clampcoagulator in accordance with the present invention;

FIG. 2A is an exploded perspective view of a portion of a clampcoagulator in accordance with the present invention;

FIG. 2B is an exploded perspective view of a portion of a clampcoagulator in accordance with the present invention;

FIG. 3 is a partially sectioned plan view of a clamp coagulator inaccordance with the present invention with the clamp arm assembly shownin an open position;

FIG. 4 is a partially sectioned plan view of a clamp coagulator inaccordance with the present invention with the clamp arm assembly shownin a closed position;

FIG. 5 is a side view of a collar cap of the clamp coagulator;

FIG. 6 is a front view of a collar cap of the clamp coagulator;

FIG. 7 is a side view of a force limiting spring of the clampcoagulator;

FIG. 8 is a front view of a force limiting spring of the clampcoagulator;

FIG. 9 is a side view of a washer of the clamp coagulator;

FIG. 10 is a front view of a washer of the clamp coagulator;

FIG. 11 is a side view of a tubular collar of the clamp coagulator;

FIG. 12 is a rear view of a tubular collar of the clamp coagulator;

FIG. 13 is a front view of a tubular collar of the clamp coagulator;

FIG. 14 is a side view of an inner knob of the clamp coagulator;

FIG. 15 is a front view of an inner knob of the clamp coagulator;

FIG. 16 is a bottom view of an inner knob of the clamp coagulator;

FIG. 17 is a rear view of an outer knob of the clamp coagulator;

FIG. 18 is a top view of an outer knob of the clamp coagulator;

FIG. 19 is a top view of a yoke of the clamp coagulator;

FIG. 20 is a side view of a yoke of the clamp coagulator;

FIG. 21 is a front view of a yoke of the clamp coagulator;

FIG. 22 is a perspective view of a yoke of the clamp coagulator;

FIG. 23 is a perspective view of an end-effector of the clampcoagulator;

FIG. 24 is a top perspective view of a clamp arm of the camp coagulator;

FIG. 25 is a top view of an end-effector of the clamp coagulator;

FIG. 26 is a side view of an end-effector of the clamp coagulator withthe clamp arm open;

FIG. 27 is a top view of a tissue pad of the clamp coagulator;

FIG. 28 is a side view of a tissue pad of the clamp coagulator;

FIG. 29 is a front view of a tissue pad of the clamp coagulator;

FIG. 30 is a perspective view of a tissue pad of the clamp coagulator;

FIG. 31 is a bottom perspective view of a clamp arm of the clampcoagulator;

FIG. 32 is a first cross-sectional view of the clamp arm illustrated inFIG. 31;

FIG. 33 is a second cross-sectional view of the clamp arm illustrated inFIG. 31;

FIG. 34 is a bottom plan view of a blade of the clamp coagulator;

FIG. 35 is a cross-sectional view of a blade of the clamp coagulator;

FIG. 35A is a cross-sectional view of an alternate embodiment of a bladeof the clamp coagulator; and

FIG. 36 is a perspective view of an end-effector of the clampcoagulator.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in combination with ultrasonicinstruments as described herein. Such description is exemplary only, andis not intended to limit the scope and applications of the invention.For example, the invention is useful in combination with a multitude ofultrasonic instruments including those described in, for example, U.S.Pat. Nos. 5,938,633; 5,935,144; 5,944,737; 5,322,055, 5,630,420; and5,449,370.

FIG. 1 illustrates ultrasonic system 10 comprising an ultrasonic signalgenerator 15 with ultrasonic transducer 82, hand piece housing 20, andclamp coagulator 120 in accordance with the present invention. Clampcoagulator 120 may be used for open or laparoscopic surgery. Theultrasonic transducer 82, which is known as a “Langevin stack”,generally includes a transduction portion 90, a first resonator orend-bell 92, and a second resonator or fore-bell 94, and ancillarycomponents. The ultrasonic transducer 82 is preferably an integralnumber of one-half system wavelengths (nλ/2) in length as will bedescribed in more detail later. An acoustic assembly 80 includes theultrasonic transducer 82, mount 36, velocity transformer 64 and surface95.

The distal end of end-bell 92 is connected to the proximal end oftransduction portion 90, and the proximal end of fore-bell 94 isconnected to the distal end of transduction portion 90. Fore-bell 94 andend-bell 92 have a length determined by a number of variables, includingthe thickness of the transduction portion 90, the density and modulus ofelasticity of the material used to manufacture end-bell 92 and fore-bell94, and the resonant frequency of the ultrasonic transducer 82. Thefore-bell 94 may be tapered inwardly from its proximal end to its distalend to amplify the ultrasonic vibration amplitude as velocitytransformer 64, or alternately may have no amplification.

The piezoelectric elements 100 may be fabricated from any suitablematerial, such as, for example, lead zirconate-titanate, leadmeta-niobate, lead titanate, or other piezoelectric crystal material.Each of the positive electrodes 96, negative electrodes 98, andpiezoelectric elements 100 has a bore extending through the center. Thepositive and negative electrodes 96 and 98 are electrically coupled towires 102 and 104, respectively. Wires 102 and 104 are encased withincable 25 and electrically connectable to ultrasonic signal generator 15of ultrasonic system 10.

Ultrasonic transducer 82 of the acoustic assembly 80 converts theelectrical signal from ultrasonic signal generator 15 into mechanicalenergy that results in primarily longitudinal vibratory motion of theultrasonic transducer 82 and an end-effector 180 at ultrasonicfrequencies. A suitable generator is available as model number GEN01,from Ethicon Endo-Surgery, Inc., Cincinnati, Ohio. When the acousticassembly 80 is energized, a vibratory motion standing wave is generatedthrough the acoustic assembly 80. The amplitude of the vibratory motionat any point along the acoustic assembly 80 depends on the locationalong the acoustic assembly 80 at which the vibratory motion ismeasured. A minimum or zero crossing in the vibratory motion standingwave is generally referred to as a node (i.e., where motion is usuallyminimal), and an absolute value maximum or peak in the standing wave isgenerally referred to as an anti-node. The distance between an anti-nodeand its nearest node is one-quarter wavelength (λ/4).

Wires 102 and 104 transmit the electrical signal from the ultrasonicsignal generator 15 to positive electrodes 96 and negative electrodes98. The piezoelectric elements 100 are energized by an electrical signalsupplied from the ultrasonic signal generator 15 in response to a footswitch 118 to produce an acoustic standing wave in the acoustic assembly80. The electrical signal causes disturbances in the piezoelectricelements 100 in the form of repeated small displacements resulting inlarge compression forces within the material. The repeated smalldisplacements cause the piezoelectric elements 100 to expand andcontract in a continuous manner along the axis of the voltage gradient,producing longitudinal waves of ultrasonic energy. The ultrasonic energyis transmitted through the acoustic assembly 80 to the end-effector 180.

In order for the acoustic assembly 80 to deliver energy to end-effector180, all components of acoustic assembly 80 must be acoustically coupledto the ultrasonically active portions of clamp coagulator 120. Thedistal end of the ultrasonic transducer 82 may be acoustically coupledat surface 95 to the proximal end of an ultrasonic waveguide 179 by athreaded connection such as stud 50.

The components of the acoustic assembly 80 are preferably acousticallytuned such that the length of any assembly is an integral number ofone-half wavelengths (nλ/2), where the wavelength λ is the wavelength ofa pre-selected or operating longitudinal vibration drive frequency f_(d)of the acoustic assembly 80, and where n is any positive integer. It isalso contemplated that the acoustic assembly 80 may incorporate anysuitable arrangement of acoustic elements.

Referring now to FIGS. 2A and 2B, a clamp coagulator 120 of the surgicalsystem 10 in accordance with the present invention is illustrated. Theclamp coagulator 120 is preferably attached to and removed from theacoustic assembly 80 as a unit. The proximal end of the clamp coagulator120 preferably acoustically couples to the distal surface 95 of theacoustic assembly 80 as shown in FIG. 1. It will be recognized that theclamp coagulator 120 may be coupled to the acoustic assembly 80 by anysuitable means.

The clamp coagulator 120 preferably includes an instrument housing 130,and an elongated member 150. The elongated member 150 can be selectivelyrotated with respect to the instrument housing 130 as further describedbelow. The instrument housing 130 includes a pivoting handle portion136, and a fixed handle 132A and 132B, coupled to a left shroud 134 anda right shroud 138 respectively.

The right shroud 138 is adapted to snap fit on the left shroud 134. Theright shroud 138 is preferably coupled to the left shroud 134 by aplurality of inwardly facing prongs 70 formed on the right shroud 138.The plurality of prongs 70 are arranged for engagement in correspondingholes or apertures 140, which are formed in the left shroud 134. Whenthe left shroud 134 is attached to the right shroud 138, a cavity isformed therebetween to accommodate various components, such as anindexing mechanism 255 as further described below.

The left shroud 134, and the right shroud 138 of the clamp coagulator120 are preferably fabricated from polycarbonate. It is contemplatedthat these components may be made from any suitable material withoutdeparting from the spirit and scope of the invention.

Indexing mechanism 255 is disposed in the cavity of the instrumenthousing 130. The indexing mechanism 255 is preferably coupled orattached on inner tube 170 to translate movement of the handle portion136 to linear motion of the inner tube 170 to open and close the clamparm assembly 300. When the pivoting handle portion 136 is moved towardthe fixed handle portion 130, the indexing mechanism 255 slides theinner tube 170 rearwardly to pivot the clamp arm assembly 300 into aclosed position. The movement of the pivoting handle portion 136 in theopposite direction slides the indexing mechanism 255 to displace theinner tube 170 in the opposite direction, i.e., forwardly, and hencepivot the clamp arm assembly 300 into its open position.

The indexing mechanism 255 also provides a ratcheting mechanism to allowthe elongated member 150 to rotate about its longitudinal axis relativeto instrument housing 130. The rotation of the elongated member 150enables the clamp arm assembly 300 to be turned to a selected or desiredangular position. The indexing mechanism 255 preferably includes atubular collar 260 and yoke 280.

The tubular collar 260 of the indexing mechanism 255 is preferablysnapped onto the proximal end of the inner tube 170 and keyed intoopposing openings 168. The tubular collar 260 is preferably fabricatedfrom polyetherimide. It is contemplated that the tubular collar 260 maybe constructed from any suitable material.

Tubular collar 260 is shown in greater detail in FIGS. 11 through 13.The tubular collar 260 preferably includes an enlarged section 262, anda bore 266 extending therethrough. The enlarged section 262 preferablyincludes a ring 272 formed around the periphery of the tubular collar260 to form groove 268. The groove 268 has a plurality of detents orteeth 269 for retaining the elongated member 150 in different rotationalpositions as the elongated member 150 is rotated about its longitudinalaxis. Preferably, the groove 268 has twelve ratchet teeth to allow theelongated portion to be rotated in twelve equal angular increments ofapproximately 30 degrees. It is contemplated that the tubular collar 260may have any number of teeth-like members. It will be recognized thatthe teeth-like members may be disposed on any suitable part of thetubular collar 260 without departing from the scope and spirit of thepresent invention.

Referring back now to FIGS. 2A through 4, the pivoting handle portion136 includes a thumb loop 142, a first hole 124, and a second hole 126.A pivot pin 153 is disposed through first hole 124 of handle portion 136to allow pivoting as shown by arrow 121 in FIG. 3. As thumb loop 142 ofpivoting handle portion 136 is moved in the direction of arrow 121, awayfrom instrument housing 130, a link 128 applies a forward force to yoke280, causing yoke 280 to move forward. Link 128 is connected to pivotinghandle portion 136 by a pin 129, and link 128 is connected to base 284by a pin 127.

Referring back now to FIG. 2A, yoke 280 generally includes a holding orsupporting member 282 and a base 284. The supporting member 282 ispreferably semi-circular and has a pair of opposing pawls 286 thatextend inwardly to engage with the teeth 269 of the tubular collar 260.It is contemplated that the pawls 286 may be disposed on any suitablepart of the yoke 280 for engagement with the teeth 269 of the tubularcollar 260 without departing from the spirit and scope of the invention.It will also be recognized that the yoke 280 may have any number ofratchet arms.

Yoke 280 is shown in greater detail in FIGS. 19 through 22. The pivotinghandle portion 136 preferably is partially disposed in a slot 147 of thebase 284 of the yoke 280. The base 284 also includes a base opening 287,an actuator travel stop 290, and a base pin-hole 288. The pivot pin 153is disposed through the base opening 287. Yoke 280 pawls 286 transferopening force to inner tube 170 through tubular collar 260, resulting inthe opening of clamp arm assembly 300.

The yoke 280 of the clamp coagulator 120 is preferably fabricated frompolycarbonate. The yoke 280 may also be made from a variety of materialsincluding other plastics, such as ABS, NYLON, or polyetherimide. It iscontemplated that the yoke 280 may be constructed from any suitablematerial without departing from the spirit and scope of the invention.

As illustrated in FIGS. 3 and 4, yoke 280 also transfers a closing forceto clamp arm assembly 300 as pivoting handle portion 136 is moved towardinstrument housing 130. Actuator travel stop 290 contacts pivot pin 153at the bottom of the stroke of pivoting handle portion 136, stopping anyfurther movement, or overtravel, of pivoting handle portion 136. Pawls286 of yoke 280 transfer force to tubular collar 260 through a washer151, a force limiting spring 155, and collar cap 152. Collar cap 152 isrigidly attached to tubular collar 260 after washer 151 and forcelimiting spring 155 have been assembled onto tubular collar 260 proximalto enlarged section 262. Collar cap 152 is illustrated in greater detailin FIGS. 5 and 6. Force limiting spring 155 is illustrated in greaterdetail in FIGS. 7 and 8, and washer 151 is illustrated in greater detailin FIGS. 9 and 10. Thickness of washer 151 may be adjusted during designor manufacturing of clamp coagulator 120 to alter the pre-load of forcelimiting spring 155. Collar cap 152 is attached to tubular collar 260 byultrasonic welding, but may alternately be press fit, snap fit orattached with an adhesive.

Referring to FIGS. 5 through 10, tubular collar 260, washer 151, forcelimiting spring 155, and collar cap 152 provide a force limiting featureto clamp arm assembly 300. As pivoting handle portion 136 is movedtoward instrument housing 130, clamp arm assembly 300 is rotated towardultrasonic blade 88. In order to provide both ultrasonic cutting, andhemostasis, it is desirable to limit the maximum force of clamp armassembly 300 to 0.5 to 3.0 Lbs.

FIGS. 5 and 6 illustrate collar cap 152 including a spring surface 158.FIGS. 7 and 8 illustrate force limiting spring 155 including a capsurface 156, a washer surface 157, and a plurality of spring elements159. Force limiting spring 155 is described in the art as a wave spring,due to the shape of spring elements 159. It is advantageous to use awave spring for force limiting spring 155 because it provides a highspring rate in a small physical size well suited to an ultrasonicsurgical instrument application where a central area is open forultrasonic waveguide 179. Force limiting spring 155 is biased betweenspring surface 158 of collar cap 152 and spring face 165 of washer 151.Washer 151 includes a pawl face 167 (FIGS. 9 and 10) that contacts pawls286 of yoke 280 after assembly of clamp coagulator 120 (see FIGS. 2through 4).

Referring now to FIGS. 2A, 2B, and FIGS. 14 through 18, a rotationalknob 190 is mounted on the elongated member 150 to turn the elongatedmember 150 so that the tubular collar 260 rotates with respect to theyoke 280. The rotational knob 190 may be fabricated from polycarbonate.The rotational knob 190 may also be made from a variety of materialsincluding other plastics, such as a polyetherimide, nylon, or any othersuitable material.

The rotational knob 190 preferably has an enlarged section or outer knob192, an inner knob 194, and an axial bore 196 extending therethrough.Inner knob 194 includes keys 191 that attach cooperatively to keyways189 of outer knob 192. The outer knob 192 includes alternatinglongitudinal ridges 197 and grooves 198 that facilitate the orientationof the rotational knob 190 and the elongated member 150 by a surgeon.The axial bore 196 of the rotational knob 190 is configured to snuglyfit over the proximal end of the elongated member 150.

The inner knob 194 extends through an opening 139 in the distal end ofthe instrument housing 130. Inner knob 194 includes a channel 193 torotatably attach inner knob 194 into opening 139. The inner knob 194 ofthe rotational knob 190 has a pair of opposing holes 199. The opposingholes 199 are aligned as part of a passageway 195 that extends throughthe elongated member 150, as will be described later.

A coupling member, such as, for example, pin 163, may be positionedthrough opposing holes 199 of the passageway 195. The pin 163 may beheld in the passageway 195 of the elongated member 150 by any suitablemeans, such as, for example, trapped between ribs in housing 130, or asilicone or cyanoacrylate adhesive. The pin 163 allows rotational torqueto be applied to the elongated member 150 from the rotational knob 190in order to rotate the elongated member 150.

When the rotational knob 190 is rotated, the teeth 269 of the tubularcollar 260 engage and ride up slightly on the corresponding pawls 286 ofthe yoke 280. As the pawls 286 ride up on the teeth 269, the supportingmember 282 of the yoke 280 deflects outwardly to allow pawls 286 to slipor pass over the teeth 269 of the tubular collar 260.

In one embodiment, the teeth 269 of the tubular collar 260 areconfigured as ramps or wedges, and the pawls 286 of the yoke 280 areconfigured as posts. The teeth 269 of the tubular collar 260 and thepawls 286 of the yoke 280 may be reversed so that the teeth 269 of thetubular collar 260 are posts, and the pawls 286 of the yoke 280 areramps or wedges. It is contemplated that the teeth 269 may be integrallyformed or coupled directly to the periphery of the elongated member 150.It will also be recognized that the teeth 269 and the pawls 286 may becooperating projections, wedges, cam surfaces, ratchet-like teeth,serrations, wedges, flanges, or the like which cooperate to allow theelongated member 150 to be indexed at selective angular positions,without departing from the spirit and scope of the invention.

As illustrated in FIG. 2B, the elongated member 150 of the clampcoagulator 120 extends from the instrument housing 130. As shown inFIGS. 2B through 4, the elongated member 150 preferably includes anouter member or outer tube 160, an inner member or inner tube 170, and atransmission component or ultrasonic waveguide 179.

The outer tube 160 of the elongated member 150 preferably includes a hub162, a tubular member 164, and a longitudinal opening or aperture 166extending therethrough. The outer tube 160 preferably has asubstantially circular cross-section and may be fabricated fromstainless steel. It will be recognized that the outer tube 160 may beconstructed from any suitable material and may have any suitablecross-sectional shape.

The hub 162 of the outer tube 160 preferably has a larger diameter thanthe tubular member 164 does. The hub 162 has a pair of outer tube holes161 to receive pin 163 to allow the hub 162 to be coupled to rotationalknob 190. As a result, the outer tube 160 will rotate when therotational knob 190 is turned or rotated.

The hub 162 of the outer tube 160 also includes wrench flats 169 onopposite sides of the hub 162. The wrench flats 169 are preferablyformed near the distal end of the hub 162. The wrench flats 169 allowtorque to be applied by a torque wrench to the hub 162 to tighten theultrasonic waveguide 179 to the stud 50 of the acoustic assembly 80. Forexample, U.S. Pat. Nos. 5,059,210 and 5,057,119, which are herebyincorporated herein by reference, disclose torque wrenches for attachingand detaching a transmission component to a mounting device of a handpiece assembly.

Located at the distal end of the tubular member 164 of the outer tube160 is an end-effector 180 for performing various tasks, such as, forexample, grasping tissue, cutting tissue and the like. It iscontemplated that the end-effector 180 may be formed in any suitableconfiguration.

End-effector 180 and its components are shown in greater detail in FIGS.23 through 33. The end-effector 180 generally includes a non-vibratingclamp arm assembly 300 to, for example, grip tissue or compress tissueagainst the ultrasonic blade 88. The end-effector 180 is illustrated inFIGS. 23 and 26 in a clamp open position, and clamp arm assembly 300 ispreferably pivotally attached to the distal end of the outer tube 160.

Looking first to FIGS. 23 through 26, the clamp arm assembly 300preferably includes a clamp arm 202, a jaw aperture 204, a first post206A, a second post 206B, and a tissue pad 208. The clamp arm 202 ispivotally mounted about a pivot pin 207A and pivot pin 207B to rotate inthe direction of arrow 122 in FIG. 3 when thumb loop 142 is moved in thedirection indicated by arrow 121 in FIG. 3. By advancing the pivotinghandle portion 136 toward the instrument housing 130, the clamp arm 202is pivoted about the pivot pin 207A and pivot pin 207B into a closedposition. Retracting the pivoting handle portion 136 away from theinstrument housing 130 pivots the clamp arm 202 into an open position.

The clamp arm 202 has tissue pad 208 attached thereto for squeezingtissue between the ultrasonic blade 88 and clamp arm assembly 300. Thetissue pad 208 is preferably formed of a polymeric or other compliantmaterial and engages the ultrasonic blade 88 when the clamp arm 202 isin its closed position. Preferably, the tissue pad 208 is formed of amaterial having a low coefficient of friction but which has substantialrigidity to provide tissue-grasping capability, such as, for example,TEFLON, a trademark name of E. I. Du Pont de Nemours and Company for thepolymer polytetraflouroethylene (PTFE). The tissue pad 208 may bemounted to the clamp arm 202 by an adhesive, or preferably by amechanical fastening arrangement as will be described below.

As illustrated in FIGS. 23, 26 and 28, serrations 210 are formed in theclamping surfaces of the tissue pad 208 and extend perpendicular to theaxis of the ultrasonic blade 88 to allow tissue to be grasped,manipulated, coagulated and cut without slipping between the clamp arm202 and the ultrasonic blade 88.

Tissue pad 208 is illustrated in greater detail in FIGS. 27 through 29.Tissue pad 208 includes a T-shaped protrusion 212, a left protrusionsurface 214, a right protrusion surface 216, a top surface 218, and abottom surface 219. Bottom surface 219 includes the serrations 210previously described. Tissue pad 208 also includes a beveled front end209 to ease insertion during assembly as will be described below.

Referring now to FIG. 26, the distal end of the tubular member 174 ofthe inner tube 170 preferably includes a finger or flange 171 thatextends therefrom. The flange 171 has an opening 173A and an opening173B (not shown) to receive the first post 206A and second post 206B ofthe clamp arm 202. When the inner tube 170 of the elongated member 150is moved axially, the flange 171 moves forwardly or rearwardly whileengaging the first post 206A and second post 206B of the clamp armassembly 300 to open and close the clamp arm 202.

Referring now to FIGS. 24, 25, and 31 through 33, the clamp arm 202 ofend-effector 180 is shown in greater detail. Clamp arm 202 includes anarm top 228 and an arm bottom 230, as well as a straight portion 235 anda curved portion 236. Straight portion 235 includes a straight T-slot226. Curved portion 236 includes a first top hole 231, a second top hole232, a third top hole 233, a fourth top hole 234, a first bottom cut-out241, a second bottom cut-out 242, a third bottom cut-out 243, a forthbottom cut-out 244, a first ledge 221, a second ledge 222, a third ledge223, a fourth ledge 224, and a fifth ledge 225.

Top hole 231 extends from arm top 228 through clamp arm 202 to secondledge 222. Top hole 232 extends from arm top 228 through clamp arm 202to third ledge 223. Top hole 233 extends from arm top 228 through clamparm 202 to fourth ledge 224. Top hole 234 extends from arm top 228through clamp arm 202 to fifth ledge 225. The arrangement of holes 231through 234 and ledges 211 through 225 enables clamp arm 202 to includeboth the straight portion 235 and the curved portion 236, while beingmoldable from a process such as, for example, metal injection molding(MIM). Clamp arm 202 may be made out of stainless steel or othersuitable metal utilizing the MIM process.

Referring to FIGS. 30 and 31, tissue pad 208 T-shaped protrusion 212 isinsertable into clamp arm 202 straight T-slot 226. Clamp arm 202 isdesigned such that tissue pad 208 may be manufactured as a straightcomponent by, for example, injection molding, machining, or extrusion.As clamp arm 202 is inserted into straight T-slot 226 and movedprogressively through curved portion 236, beveled front edge 209facilitates bending of tissue pad 208 to conform to the curvature ofclamp arm 202. The arrangement of holes 231 through 234 and ledges 211through 225 enables clamp arm 202 to bend and hold tissue pad 208.

FIGS. 32 and 33 illustrate how clamp arm 202 holds tissue pad 208 inplace while maintaining a bend in tissue pad 208 that conforms to curvedportion 236 of clamp arm 202. As illustrated in FIG. 32, third ledge 223contacts right protrusion surface 216 providing a contact edge 238,while left protrusion surface 214 is unsupported at this position. At adistal location, illustrated in FIG. 33, fourth ledge 224 contacts leftprotrusion surface 214 providing a contact edge 239, while rightprotrusion surface 216 is unsupported at this location.

Referring back now to FIG. 2 again, the inner tube 170 of the elongatedmember 150 fits snugly within the opening 166 of the outer tube 160. Theinner tube 170 preferably includes an inner hub 172, a tubular member174, a circumferential groove 176, a pair of opposing openings 178, apair of opposing openings 178, and a longitudinal opening or aperture175 extending therethrough. The inner tube 170 preferably has asubstantially circular cross-section, and may be fabricated fromstainless steel. It will be recognized that the inner tube 170 may beconstructed from any suitable material and may be any suitable shape.

The inner hub 172 of the inner tube 170 preferably has a larger diameterthan the tubular member 174 does. The pair of opposing openings 178 ofthe inner hub 172 allow the inner hub 172 to receive the pin 163 toallow the inner tube 170 and the ultrasonic waveguide 179 to transfertorque for attaching ultrasonic waveguide 179 to stud 50 as previouslydescribed. An O-ring 220 is preferably disposed in the circumferentialgroove 176 of the inner hub 172.

The ultrasonic waveguide 179 of the elongated member 150 extends throughaperture 175 of the inner tube 170. The ultrasonic waveguide 179 ispreferably substantially semi-flexible. It will be recognized that theultrasonic waveguide 179 may be substantially rigid or may be a flexiblewire. Ultrasonic vibrations are transmitted along the ultrasonicwaveguide 179 in a longitudinal direction to vibrate the ultrasonicblade 88.

The ultrasonic waveguide 179 may, for example, have a lengthsubstantially equal to an integral number of one-half system wavelengths(nλ/2). The ultrasonic waveguide 179 may be preferably fabricated from asolid core shaft constructed out of material which propagates ultrasonicenergy efficiently, such as titanium alloy (i.e., Ti—6Al—4V) or analuminum alloy. It is contemplated that the ultrasonic waveguide 179 maybe fabricated from any other suitable material. The ultrasonic waveguide179 may also amplify the mechanical vibrations transmitted to theultrasonic blade 88 as is well known in the art.

As illustrated in FIG. 2, the ultrasonic waveguide 179 may include oneor more stabilizing silicone rings or damping sheaths 110 (one beingshown) positioned at various locations around the periphery of theultrasonic waveguide 179. The damping sheaths 110 dampen undesirablevibration and isolate the ultrasonic energy from the inner tube 170assuring the flow of ultrasonic energy in a longitudinal direction tothe distal end of the ultrasonic blade 88 with maximum efficiency. Thedamping sheaths 110 may be secured to the ultrasonic waveguide 179 by aninterference fit such as, for example, a damping sheath described inU.S. patent application Ser. No. 08/808,652 hereby incorporated hereinby reference.

Referring again to FIG. 2, the ultrasonic waveguide 179 generally has afirst section 182, a second section 184, and a third section 186. Thefirst section 182 of the ultrasonic waveguide 179 extends distally fromthe proximal end of the ultrasonic waveguide 179. The first section 182has a substantially continuous cross-section dimension.

The first section 182 preferably has at least one radial waveguide hole188 extending therethrough. The waveguide hole 188 extends substantiallyperpendicular to the axis of the ultrasonic waveguide 179. The waveguidehole 188 is preferably positioned at a node but may be positioned at anyother suitable point along the ultrasonic waveguide 179. It will berecognized that the waveguide hole 188 may have any suitable depth andmay be any suitable shape.

The waveguide hole 188 of the first section 182 is aligned with theopposing openings 178 of the hub 172 and outer tube holes 161 of hub 162to receive the pin 163. The pin 163 allows rotational torque to beapplied to the ultrasonic waveguide 179 from the rotational knob 190 inorder to rotate the elongated member 150. Passageway 195 of elongatedmember 150 includes opposing openings 178, outer tube holes 161,waveguide hole 188, and opposing holes 199.

The second section 184 of the ultrasonic waveguide 179 extends distallyfrom the first section 182. The second section 184 has a substantiallycontinuous cross-section dimension. The diameter of the second section184 is smaller than the diameter of the first section 182. As ultrasonicenergy passes from the first section 182 of the ultrasonic waveguide 179into the second section 184, the narrowing of the second section 184will result in an increased amplitude of the ultrasonic energy passingtherethrough.

The third section 186 extends distally from the distal end of the secondsection 184. The third section 186 has a substantially continuouscross-section dimension. The third section 186 may also include smalldiameter changes along its length. The third section preferably includesa seal 187 formed around the outer periphery of the third section 186.As ultrasonic energy passes from the second section 184 of theultrasonic waveguide 179 into the third section 186, the narrowing ofthe third section 186 will result in an increased amplitude of theultrasonic energy passing therethrough.

The third section 186 may have a plurality of grooves or notches (notshown) formed in its outer circumference. The grooves may be located atnodes of the ultrasonic waveguide 179 or any other suitable point alongthe ultrasonic waveguide 179 to act as alignment indicators for theinstallation of a damping sheath 110 during manufacturing.

Still referring to FIG. 2, damping sheath 110 of the surgical instrument150 surrounds at least a portion of the ultrasonic waveguide 179. Thedamping sheath 110 may be positioned around the ultrasonic waveguide 179to dampen or limit transverse side-to-side vibration of the ultrasonicwaveguide 179 during operation. The damping sheath 110 preferablysurrounds part of the second section 184 of the ultrasonic waveguide179. It is contemplated that the damping sheath 110 may be positionedaround any suitable portion of the ultrasonic waveguide 179. The dampingsheath 110 preferably extends over at least one antinode of transversevibration, and more preferably, a plurality of antinodes of transversevibration. The damping sheath 110 preferably has a substantiallycircular cross-section. It will be recognized that the damping sheath110 may have any suitable shape to fit over the ultrasonic waveguide 179and may be any suitable length.

The damping sheath 110 is preferably in light contact with theultrasonic waveguide 179 to absorb unwanted ultrasonic energy from theultrasonic waveguide 179. The damping sheath 110 reduces the amplitudeof non-axial vibrations of the ultrasonic waveguide 179, such as,unwanted transverse vibrations associated with the longitudinalfrequency of 55,500 Hz as well as other higher and lower frequencies.

The damping sheath 110 is constructed of a polymeric material,preferably with a low coefficient of friction to minimize dissipation ofenergy from the axial motion or longitudinal vibration of the ultrasonicwaveguide 179. The polymeric material is preferably floura-ethylenepropene (FEP) which resists degradation when sterilized using gammaradiation. It will be recognized that the damping sheath 110 may befabricated from any suitable material, such as, for example, PTFE.

The damping sheath 110 preferably has an opening extending therethrough,and a longitudinal slit 111. The slit 111 of the damping sheath 110allows the damping sheath 110 to be assembled over the ultrasonicwaveguide 179 from either end. It will be recognized that the dampingsheath 110 may have any suitable configuration to allow the dampingsheath 110 to fit over the ultrasonic waveguide 179. For example, thedamping sheath 110 may be formed as a coil or spiral or may havepatterns of longitudinal and/or circumferential slits or slots. It isalso contemplated that the damping sheath 110 may be fabricated withouta slit 111 and the ultrasonic waveguide 179 may be fabricated from twoor more parts to fit within the damping sheath 110.

It will be recognized that the ultrasonic waveguide 179 may have anysuitable cross-sectional dimension. For example, the ultrasonicwaveguide 179 may have a substantially uniform cross-section or theultrasonic waveguide 179 may be tapered at various sections or may betapered along its entire length.

The ultrasonic waveguide 179 may also amplify the mechanical vibrationstransmitted through the ultrasonic waveguide 179 to the ultrasonic blade88 as is well known in the art. The ultrasonic waveguide 179 may furtherhave features to control the gain of the longitudinal vibration alongthe ultrasonic waveguide 179 and features to tune the ultrasonicwaveguide 179 to the resonant frequency of the system.

The proximal end of the third section 186 of ultrasonic waveguide 179may be coupled to the distal end of the second section 184 by aninternal threaded connection, preferably near an antinode. It iscontemplated that the third section 186 may be attached to the secondsection 184 by any suitable means, such as a welded joint or the like.Third section 186 includes ultrasonic blade 88. Although the ultrasonicblade 88 may be detachable from the ultrasonic waveguide 179, theultrasonic blade 88 and ultrasonic waveguide 179 are preferably formedas a single unit.

The ultrasonic blade 88 may have a length substantially equal to anintegral multiple of one-half system wavelengths (nλ/2). The distal endof ultrasonic blade 88 may be disposed near an antinode in order toprovide the maximum longitudinal excursion of the distal end. When thetransducer assembly is energized, the distal end of the ultrasonic blade88 is configured to move in the range of, for example, approximately 10to 500 microns peak-to-peak, and preferably in the range of about 30 to150 microns at a predetermined vibrational frequency.

The ultrasonic blade 88 is preferably made from a solid core shaftconstructed of material which propagates ultrasonic energy, such as atitanium alloy (i.e., Ti—6Al—4V) or an aluminum alloy. It will berecognized that the ultrasonic blade 88 may be fabricated from any othersuitable material. It is also contemplated that the ultrasonic blade 88may have a surface treatment to improve the delivery of energy anddesired tissue effect. For example, the ultrasonic blade 88 may bemicro-finished, coated, plated, etched, grit-blasted, roughened orscored to enhance coagulation and cutting of tissue and/or reduceadherence of tissue and blood to the end-effector. Additionally, theultrasonic blade 88 may be sharpened or shaped to enhance itscharacteristics. For example, the ultrasonic blade 88 may be bladeshaped, hook shaped, or ball shaped.

As illustrated in FIGS. 34, 35 and 36, the geometry of the ultrasonicblade 88 in accordance with the present invention delivers ultrasonicpower more uniformly to clamped tissue than predicate devices. Theend-effector 180 provides for improved visibility of the blade tip sothat a surgeon can verify that the blade 88 extends across the structurebeing cut or coagulated. This is especially important in verifyingmargins for large blood vessels. The geometry also provides for improvedtissue access by more closely replicating the curvature of biologicalstructures. Blade 88 provides a multitude of edges and surfaces,designed to provide a multitude of tissue effects: clamped coagulation,clamped cutting, grasping, back-cutting, dissection, spot coagulation,tip penetration and tip scoring.

The distal most tip of blade 88 has a surface 54 perpendicular totangent 63, a line tangent to the curvature at the distal tip. Twofillet-like features 61A and 61B are used to blend surfaces 51, 52 and54, thus giving a blunt tip that can be utilized for spot coagulation.The top of the blade 88 is radiused and blunt, providing a broad edge,or surface 56, for clamping tissues between it and clamp arm assembly300. Surface 56 is used for clamped cutting and coagulation as well asmanipulating tissues while the blade is inactive.

The bottom surface has a spherical cut 53 that provides a narrow edge,or sharp edge 55, along the bottom of blade 88. The material cut isaccomplished by, for example, sweeping a spherical end mill through anarc of radius R1 and then finishing the cut using a second, tighterradius R2 that blends the cut with a bottom surface 58 of the blade 88.Radius R1 is preferably within the range of 0.5 inches to 2 inches, morepreferably within the range of 0.9 inches to 1.1 inches, and mostpreferably about 1.068 inches. Radius R2 is preferably within the rangeof 0.125 inches to 0.5 inches, and most preferably about 0.25 inches.The second radius R2 and the corresponding blend with the bottom surface58 of blade 88 diminishes the stress concentrated at the end of thespherical cut relative to stopping the cut without this blend. The sharpedge 55 facilitates dissection and unclamped cutting (back-cutting)through less vascular tissues.

Spherical cut 53 on bottom surface 58 of blade 88 creates sharp edge 55while removing a minimal amount of material from blade 88. Spherical cut53 on the bottom of blade 88 creates a sharp edge 55 with an angle of αas described below. This angle α may be similar to predicate shearsdevices such as, for example, the LCS-K5 manufactured by EthiconEndo-Surgery, Inc., Cincinnati, Ohio. However the blade 88 of thepresent invention cuts faster than predicate devices by virtue of theorientation of the angle α with respect to the typical applicationforce. For the predicate shears devices, the edges are symmetric,spanning the application force equally. The edges for the presentinvention are asymmetric, with the asymmetry of the edges dictating howquickly tissue is separated or cut. The asymmetry is important in thatit provides for an effectively sharper edge when ultrasonicallyactivated, without removing a significant volume of material, whilemaintaining blunt geometry. This asymmetric angle as well as thecurvature of the blade act to self tension tissue during back-cuttingutilizing a slight hook-like or wedge-like action.

Sharp edge 55 of ultrasonic blade 88 is defined by the intersection ofsurface 53 and a second surface 57 left after bottom surface 58 hasreceived spherical cut 53. Clamp arm assembly 300 is pivotally mountedon said distal end of outer tube 160 for pivotal movement with respectto ultrasonic blade 88, for clamping tissue between clamp arm assembly300 and ultrasonic blade 88. Reciprocal movement of inner tube 170pivots clamp arm assembly 300 through an arc of movement, defining avertical plane 181. A tangent 60 of spherical cut 53 at sharp edge 55defines an angle α with a tangent 62 of second surface 57, asillustrated in FIG. 35. The bisection 59 of angle α preferably does notlie in vertical plane 181, but is offset by an angle β. Preferably thetangent 60 of spherical cut 53 lies within about 5 to 50 degrees ofvertical plane 181, and most preferably the tangent of spherical cut 53lies about 38.8 degrees from vertical plane 181. Preferably angle α iswithin the range of about 90 to 150 degrees, and most preferably angle αis about 121.6 degrees.

Looking to FIG. 35A, an alternate embodiment of the present invention isillustrated with an asymmetric narrow edge. A tangent 60A of a sphericalcut 53A at a sharp edge 55A defines an angle αA with a tangent 62A of asecond surface 57A, as illustrated in FIG. 35A. A bisection 59A of angleαA preferably does not lie in a vertical plane 181A, but is offset by anangle βA.

The curved shape of the design of ultrasonic blade 88 also results in amore uniformly distributed energy delivery to tissue as it is clampedagainst the blade 88. Uniform energy delivery is desired so that aconsistent tissue effect (thermal and transection effect) along thelength of end effector 180 is achieved. The distal most 15 millimetersof blade 88 is the working portion, used to achieve a tissue effect. Aswill be further described below, the displacement vectors for locationsalong the curved shears blade 88 have directions that, by virtue of theimprovements of the present invention over predicate instruments, lielargely in the x-y plane illustrated in FIGS. 34 and 35. The motion,therefore, of blade 88 lies within a plane (the x-y plane) that isperpendicular to the direction of the clamping force from clamp armassembly 300.

Straight symmetric ultrasonic blades in general have tip excursions thatlie along the longitudinal axis, designated the x-axis in FIGS. 34 and35. Transverse motion is usually undesirable because it results inundesirable heat generation in inner tube 170. When a functionalasymmetry is added to an ultrasonic blade, such as a curved end-effectoras described in U.S. patent application Ser. No. 09/106,686 previouslyincorporated herein by reference, the functional asymmetry creates animbalance in the ultrasonic waveguide. If the imbalance is notcorrected, then undesirable heat, noise, and compromised tissue effectoccur. Although U.S. patent application Ser. No. 09/106,686 teaches howto provide ultrasonic blades that are balanced proximal to the balanceasymmetry, the distal portion of the end-effector has an excursion in atleast two axes. If the end-effector has a single plane of functionalasymmetry, such as a curved end-effector, but the blade is otherwisesymmetric, then the excursion will lie in a plane at the distal mostend.

It is often desirable to minimize any ultrasonic blade 88 excursion inthe z-axis direction. Excursion of ultrasonic blade 88 in the z-axisdirection causes system inefficiencies, resulting in undesirableheating, power loss, and possibly noise. Excursion of ultrasonic blade88 in the z-axis direction at end-effector 180 causes the ultrasonicblade 88 to impact tissue lying between ultrasonic blade 88 and clamparm assembly 300. It is desirable to limit ultrasonic blade 88 excursionto the x-y plane shown in FIGS. 34 and 35. This allows ultrasonic blade88 to rub tissue lying between ultrasonic blade 88 and clamp armassembly 300 without impact, which optimizes heating of the tissue, andthus provides optimal coagulation. Minimizing z-axis excursion bothproximal to the end-effector 180, and in ultrasonic blade 88, may beaccomplished by proper selection of a spherical cut 53.

However, an ultrasonic end-effector 180 with an ultrasonic blade 88 thathas multiple functional asymmetries, such as ultrasonic blade 88 asillustrated in FIGS. 34 through 36, will naturally have a tendency toinclude tip excursion in all three axes, x, y, and z if not balancedproperly. For example, ultrasonic blade 88 as illustrated in FIG. 34 iscurved in the y direction at its distal end. This curvature, althoughbalanced proximal to end-effector 180, will cause ultrasonic blade 88 tohave excursions in both the x and y directions when activated. Addingspherical cut 53 subsequently adds another level of asymmetry toultrasonic blade 88, causing tip excursion in all three axes if notcorrected, and also causing z-axis imbalances in ultrasonic waveguide179 which decreases efficiency.

It is possible to minimize z-axis tip excursion proximal to thefunctional asymmetry, and therefore maximize efficiency with improvedtissue effect, by providing a functional asymmetry optimized to minimizez-axis excursion in ultrasonic waveguide 179. As illustrated in FIG. 34,spherical cut 53 may extend proximally into ultrasonic blade 88, fromthe most distal end, to any position. For example, FIG. 34 illustrates afirst position 66, a second position 67, and a third position 68, forspherical cut 53 to extend into ultrasonic blade 88.

Table 1 below describes three possible lengths of spherical cuts 53 forultrasonic blade 88 illustrated in FIG. 34 as first position 66, secondposition 67, and third position 68. The rows of Table 1 correspond tothe length of cut into the ultrasonic blade 88, and the columns of Table1 correspond to the balance condition and excursions along each axis foreach cut length. It can be appreciated from Table 1 that providingspherical cut 53 to a length corresponding to first position 68minimizes the z axis excursion proximal to the functional asymmetry. Itis preferable to balance ultrasonic blade 88 below 15% z axis excursionproximal to the functional asymmetry and it is most preferable tobalance ultrasonic blade 88 below 5% z axis excursion proximal to thefunctional asymmetry. Preferably clamp coagulator 120 is designed to bebalanced when activated in air (loaded only by air), and then balance isverified under other load conditions.

In Table 1, a normalized excursion percentage (% z) in a clampinginstrument at the end-effector 88 is calculated by taking the magnitudeof the excursion in the direction normal to the clamp arm when the clamparm is in its fully closed position, and dividing that magnitude by themagnitude of the maximum tip vibration excursion (also called theprimary tip vibration excursion), and then multiplying the dividend byone hundred. Primary tip vibration excursion is the magnitude of themajor axis of the ellipse or ellipsoid created by a point on the distalmost end of ultrasonic blade 88 when the ultrasonic blade 88 isactivated. The measurement of excursions is more fully explained in IECinternational standard 61847, titled Measurement and Declaration of theBasic Output Characteristics of ultrasonic surgical systems, herebyincorporated herein by reference. A normalized excursion percentage (%x, % y, % z) in ultrasonic blade 88 or ultrasonic waveguide 179 iscalculated by taking the magnitude of a secondary vibration excursion,and dividing that magnitude by the magnitude of the primary tipvibration excursion, and then multiplying the dividend by one hundred.Secondary tip vibration excursion is the magnitude of a minor axis, orother arbitrary axis, of the ellipse or ellipsoid created by a point onthe distal most end of ultrasonic blade 88 when the ultrasonic blade 88is activated. Table 1. Three possible lengths to provide a range ofbalances for a 0.946 inch long blade with a radius of R1 manufacturedfrom Ti6Al4V with the blade including a functional asymmetry.

% z % x at distal % y at distal % z at distal proximal end of blade endof blade end of blade to blade 88 88 88 88 Cut Length = 71.83 69.47 4.150.40 12.8 mm, Location at first position 68 Cut Length = 72.49 68.871.60 12.43 14.8 mm, Location at second position 67 Cut Length = 74.5466.03 9.21 8.25 8.2 mm, Location at third position 66

Referring now to FIGS. 1-4, the procedure to attach and detach the clampcoagulator 120 from the acoustic assembly 80 will be described below.When the physician is ready to use the clamp coagulator 120, thephysician simply attaches the clamp coagulator 120 onto the acousticassembly 80. To attach the clamp coagulator 120 to acoustic assembly 80,the distal end of stud 50 is threadedly connected to the proximal end ofthe transmission component or ultrasonic waveguide 179. The clampcoagulator 120 is then manually rotated in a conventionalscrew-threading direction to interlock the threaded connection betweenthe stud 50 and the ultrasonic waveguide 179.

Once the ultrasonic waveguide 179 is threaded onto the stud 50, a tool,such as, for example, a torque wrench, may be placed over the elongatedmember 150 of the clamp coagulator 120 to tighten the ultrasonicwaveguide 179 to the stud 50. The tool may be configured to engage thewrench flats 169 of the hub 162 of the outer tube 160 in order totighten the ultrasonic waveguide 179 onto the stud 50. As a result, therotation of the hub 162 will rotate the elongated member 150 until theultrasonic waveguide 179 is tightened against the stud 50 at a desiredand predetermined torque. It is contemplated that the torque wrench mayalternately be manufactured as part of the clamp coagulator 120, or aspart of the hand piece housing 20, such as the torque wrench describedin U.S. Pat. No. 5,776,155 hereby incorporated herein by reference.

Once the clamp coagulator 120 is attached to the acoustic assembly 80,the surgeon can rotate the rotational knob 190 to adjust the elongatedmember 150 at a desired angular position. As the rotational knob 190 isrotated, the teeth 269 of the tubular collar 260 slip over the pawls 286of the yoke 280 into the adjacent notch or valley. As a result, thesurgeon can position the end-effector 180 at a desired orientation.Rotational knob 190 may incorporate an indicator to indicate therotational relationship between instrument housing 130 and clamp arm202. As illustrated in FIGS. 17 and 18, one of the ridges 197 ofrotational knob 190 may be used to indicate the rotational position ofclamp arm 202 with respect to instrument housing 130 by utilizing, forexample, an enlarged ridge 200. It is also contemplated that alternateindications such as the use of coloring, symbols, textures, or the likemay also be used on rotational knob 190 to indicate position similarlyto the use of enlarged ridge 200.

To detach the clamp coagulator 120 from the stud 50 of the acousticassembly 80, the tool may be slipped over the elongated member 150 ofthe surgical tool 120 and rotated in the opposite direction, i.e., in adirection to unthread the ultrasonic waveguide 179 from the stud 50.When the tool is rotated, the hub 162 of the outer tube 160 allowstorque to be applied to the ultrasonic waveguide 179 through the pin 163to allow a relatively high disengaging torque to be applied to rotatethe ultrasonic waveguide 179 in the unthreading direction. As a result,the ultrasonic waveguide 179 loosens from the stud 50. Once theultrasonic waveguide 179 is removed from the stud 50, the entire clampcoagulator 120 may be thrown away.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. Accordingly, it isintended that the invention be limited only by the spirit and scope ofthe appended claims.

What is claimed is:
 1. A blade for an ultrasonic surgical instrumentcomprising: a proximal end; a distal end; a broad edge defined by afirst and second parallel surface; and a narrow edge, wherein saidnarrow edge is defined by the intersection of a first surface and asecond surface, wherein said first surface is concave and intersects thefirst parallel surface and the second surface is convex and intersectsthe second parallel surface.
 2. The blade according to claim 1, whereinthe first surface is defined by a radiused cut having a radius fromabout 0.5 inches to about 2.0 inches.
 3. The blade according to claim 2,wherein the first surface is further defined by a second radiused cuthaving a radius from about 0.125 inches to about 0.5 inches.
 4. Theblade according to claim 1, wherein the first surface extends proximallyinto the blade from the distal end and defining a length of the firstsurface.
 5. The blade according to claim 4, wherein the length is fromabout 8.0 mm to about 15 mm.
 6. The blade according to claim 1, whereina tangent of the first surface and a tangent of the second surfacedefine an angle from about 90° to about 150°.
 7. The blade according toclaim 1, wherein the blade is curved.
 8. A blade for an ultrasonicsurgical instrument comprising: a proximal end; a distal end; a broadedge disposed between a first and second surface; and a narrow edge,wherein said narrow edge is defined by the intersection of a firstcurved, surface and a curved second surface, wherein said first curvedsurface is concave from said intersection to the point where itintersects the first surface and the second curved surface is convexfrom said intersection to the point where it intersects the secondsurface.
 9. A blade according to claim 8, wherein the second curvedsurface is concave.
 10. The blade according to claim 8, wherein thefirst curved surface is defined by a radiused cut having a radius fromabout 0.5 inches to about 2.0 inches.
 11. The blade according to claim10, wherein the first curved surface is further defined by a secondradiused cut having a radius from about 0.125 inches to about 0.5inches.
 12. The blade according to claim 8, wherein the first curvedsurface extends proximally into the blade from the distal end anddefining a length of the first curved surface.
 13. The blade accordingto claim 12, wherein the length is from about 8.0 mm to about 15 mm. 14.The blade according to claim 8, wherein a tangent of the first curvedsurface and a tangent of the second curved surface define an angle fromabout 90° to about 150°.
 15. The blade according to claim 8, wherein theblade is curved.